Both modern screening methods and appropriate treatment modalities lead to a drastic reduction in mortality due to cervical cancer. However there is a strong need for further diagnostic improvements and less invasive treatment modalities. Photomedicine (i.e. the interaction of light and tissues) is a novel, non-invasive alternative in diagnosis and treatment of gynecological diseases. The aims of the present study were threefold 1) to determine the optical properties of normal cervical tissue 2) to assess the feasibility of differentiating normal from dysplastic cervical tissues using frequency domain photon migration (FDPM) technique and 3) to determine the changes in optical properties of cervical tissue following photodynamic therapy (PDT) of cervical dysplasia in vivo and to correlate this alteration in optical properties to PDT induced tissue reactions. From the present data we concluded 1) The FDPM technique is capable of discriminating normal from dyspla st ic cervical tissues based on differences in optical properties; and 2) CIN II and CIN III have different light scattering properties. Using FDPM technique and instrumentation, we are able to noninvasively distinguish normal from dysplastic ecto-cervical tissues and to monitor PDT induced alteration in cervical optical properties. Correlation of PDT treatment outcomes and the measured optical properties provide a powerful means to optimize PDT parameters for treatment of cervical dysplasia. Additional instrument modifications and refinement in techniques are underway to make monitor of cervical properties real-time and to enable measurement of both ecto- and endo-cervic.